US 6,078,729 A · Foam, drain and fill control system for humidifier

Abstract

The control system for a humidifier, which is part of a heat, ventilation or air conditioning HVAC system, detects the level of water and generates control signals by detecting the capacitance of the water in the humidifier. These control signals are used to fill the humidifier with water and control heater elements and, to some degree, drain cycles. A capacitor is utilized to detect the change in capacitance as the water level changes. The control circuit, coupled to the capacitor, generates fill control signals based upon first and second predetermined capacitive levels. In one embodiment, the capacitor sensor includes an electrically conductive element extending into the water as a first electrode which is shielded by an insulating cover, where the water acts as a medium through which capacitance is measured and the humidifier casing or another electrically conductive element in the water functions as the second electrode for the capacitor. Further refinements of the control system include a converter which converts the capacitive value of the capacitor into a frequency signal and a microprocessor which monitors that frequency signal to determine the capacitive level and hence the water level. Increasingly higher frequencies represent increasingly lower water levels. In an enhanced version, the control system further includes an electrically conductive sensor mounted in an interior top region of the humidifier for detecting the presence of foam thereat. When the capacitive sensor detects normal water levels and the conductive sensor mounted above normal water level detects foam, the microprocessor triggers corrective action. Corrective action consists of turning OFF power to the heater elements and initialing a drain cycle to clean out the critical level of impurities which created the foam. In another enhancement, the control system is configured as an adaptive feedback drain control system.

Claims45

Dependent claims

A control system for a humidifier adapted to be controllably filled and stocked with water, said humidifier providing humidified air for a heat, ventilation or air conditioning (HVAC) system in a building, said control system adapted to generate control signals to fill and heat said water, said humidifier having an electrically conductive casing, the control system comprising:

a capacitor disposed in said humidifier which electrically senses water level in said humidifier, said capacitor including a first electrode extending into said water and an electrically conductive second electrode, said second electrode electrically coupled to said conductive humidifier casing which acts as a capacitive electrode and said water retained by said humidifier is a medium through which capacitance is measured via said capacitor;
a control circuit electrically coupled to said capacitor, said control circuit generating said control signals based upon predetermined capacitive levels of said capacitor.

An adaptive feedback drain control system for a humidifier adapted to be filled with water and drained of water, said humidifier providing humidified air for a heat, ventilation or air conditioning (HVAC) system in a building, said control system adapted to generate fill control signals and drain control signals, the control system comprising:

a capacitor disposed in said humidifier which electrically senses water level in said humidifier;
an electrically conductive sensor, mounted in an interior top region of said humidifier, for detecting the presence of foam thereat;
a control circuit with a timer, said control circuit electrically coupled to said capacitor and said conductive sensor, said control circuit generating said fill control signals based upon first and second predetermined capacitive levels of said capacitor and generating said drain control signals based upon one of a predetermined time period and a predetermined output of said conductive sensor;
and,
means for resetting said predetermined time period to adaptively preclude detection of said foam by said conductive sensor.

2 more elements

A method of controlling a humidifier utilizing an adaptive feedback process, said humidifier being filled with water and drained of water in accordance with fill control and drain control signals, said humidifier providing humidified air to a heat, ventilation or air conditioning (HVAC) system in a building, the method comprising the steps of:

sensing the capacitance of the water in the humidifier, said capacitance varying with a water level in the humidifier;
sensing a presence of foam in an interior top region of said humidifier by detecting electrical conductivity of the foam thereat;
generating said fill control signals based upon the sensed capacitance and a comparison with first and second predetermined capacitance levels;
timing each fill and drain cycle;
generating said drain control signals based upon one of detecting said presence of said foam and an expiration of a predetermined time period;
and,
resetting said predetermined time period based upon a current time for a current fill and drain cycle upon detecting said presence of said foam.

4 more elements

Dependencies are inferred from the claim text.

Foam, drain and fill control system for humidifier

Life of this patent

Foam, drain and fill control system for humidifier

Life of this patent

Abstract

Claims45